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The Nieuwendam, in which pumping station Monnickendam is built, was constructed around the year 1400. The dam has been continuously reinforced, raised and widened over the past 600 years. Documentation of this is lacking except for the last 100 years. In order to gain more insight into the structure of the dam, research bureau Vestigia Archeologie & Cultuurhistorie from Amersfoort is conducting research into the stratification of the body of soil during the excavation of the cofferdam. This recently resulted in a fantastic archaeological find.
The Hollands Noorderkwartier Water Board lacked a complete picture of the construction of the centuries-old dam, begins Jeroen Flamman, senior KNA (Quality Standard for Dutch Archaeology) archaeologist at Vestigia and project leader of the archaeological survey. "The preliminary research did mention a sluice that would have been constructed in the Nieuwendam in the past, as evidenced by a brief description, but its exact location was not known. Historical maps from the 16th century were also inconclusive. The maps turned out not to be scale fixed and could not be placed back in the current map image so that the location of historical lock could not be determined in advance. So in principle, we would only concern ourselves with researching the construction of the dam. Until we got a call from the contractor's consortium."
During excavations in the construction pit, they came across all kinds of wood debris. "At first we were still thinking, for example, of remnants of a bank revetment or of earlier reinforcements," says Flamman. "Once we arrived on site, it turned out to be construction timber, oak wood that had been worked by people. Then the circus takes off. That eventually resulted in the fantastic find of a lock that was over 400 years old. Or rather, the underside of a lock construction, being the floor and foundation measuring 36 m in length and 6.5 m in width. After coordinating with the competent authority, we teamed up with the Hollands Noorderkwartier Water Board and the CGM contractor combination to remove the century-
and old structure as carefully as possible. The three of us each take our own role to ensure that construction work can continue as soon as possible."
As the initiator and client, the Water Board also employed a historian. "He immediately dove into the archives to bring information to the surface. We then started archaeological research on site with a large team according to the applicable laws and regulations. The contracting consortium in turn provided all kinds of equipment and personnel to assist us. In this way, everyone contributed to this investigation. Within a week and a half, all the tasks and roles were divided and hands were put together to carry out the study in an efficient manner. That is truly commendable for such a large and complex project," Flamman believes.
The century-old lock will be completely "exposed" and mapped with state-of-the-art technologies. "There will even be a 3D laser scan and a photogrammetric image of the structure," says Flamman. "From samples of the oak wood and historical descriptions, we can deduce that the lock must have been built around 1560. That in turn raises all sorts of other questions. For at that time there was little oak wood available in the Netherlands, certainly not of the size used in the lock. So the building material must have been brought in from elsewhere, such as Germany, Poland or perhaps Scandinavia. In addition, we are curious about the construction of the structure. Few specifications have survived from that time. Often there was only an order list and the construction was not captured in drawings, but built by heart by experienced carpenters, as was customary in the construction of ships at that time. Enough arguments, therefore, to carefully document the construction."
Keeping the lock was not an option, according to Flamman. "The level at which the lock was found is 2.5 meters higher than the deepest level at which the pumping station will be built," he said. However, construction elements will be preserved that will be publicly displayed at a later date. Once everything has been mapped, the contractor consortium can resume work. We will eventually compile and describe this research and this extraordinary find, along with all kinds of other objects that have emerged on the lock floor, in a beautiful book. That's what this project deserves."
